Rheostat



- March 1 1927.

H. E. ADAMS RHEOSTAT Filed Sept 14. 1925 Will afro: "u r The . thehollow of the extension spaced Patenta& Mar. 1', 1927.

&UNITED sTATEs 1-,6s,967 PATENT. OFFICE;

EABBY E. ADAMS, OI' TOLEDO, OEIQ ASSIGNOB TO THE W. G. NAGEL ELECTBICCOM- P ANY, OI' TOLEDO, OEIO, A COROBATION OF 0310 annosmr.

Application filed September 14, 1925. serial No. 53,114.

This invention relates to electrical equipv ment and particularly torheostat umts.

Inthe use of units of this character in connection, for instance, withinstruments for' 5 indicating the level of liquids it is important totightly seal the chamber containing the rheostat Contacting parts, andin doing so the leads from the outside terminal wires must be broughtinto the chamber in a sealed manner to prevent leakage therearound.

It is the object of this invention to provide a chamber means :for thispurpose, which 'is easy and quick to install, is inexpensive tomanufacture and composed of few parts.

The invention is fully described in. the following specification, andwhile in its broader aspect itiscapable of embodiment forms and-indifferent connecin numerous tions, a ,preferred embodiment thereof inconnection wi h a rheostat unit is illustrated in the accompanyingdrawings, n which,--;

Figure 1 is a top" plan view of such unit with the covers removed andthe parts broken 'awa Fig. 2 is a section on the line 2-2 in ig. 1. Fig.3 is a section on the line- 3-3 in Fig. 1. Fig. 4 is a perspective viewof the lead connections and carrying strips therefor in assembledrelation and. with parts of the strips broken away. Fig. 5 is aperspective View of one of the strips; Fig. 6 is a perspective viewof'one of the terminal clamping members, and Fig. 7 is a per- `spectiveview of the spring lead finger extending from one of the lead connectonsto -the swinging contact arm'of the rheostat.

Referrin shallow ca'sng or frame of substantially cylindrical form inthe present instance, and having' a hollow extension 2 at oneside andashenk or arm 3 projectin from its bottom substantially axially of t ebody part 1. art 1 is hollow to form an open top chamlier 4, whichsiscircular in form and in communication through an open neck 5 with 2. Asegmental resistance unit 6 is mounted concentrically in the-chamber 4with the opening between its ends in register with the neck openin 5`and having' any suitable arrangement o Contacts,

constitute the sucoessively spaced stan'ce, 7

convolutons of thearesistance wire 8 is jqurnaledin the c to thedrawings, 1 designates a 'ngs being which, in thepresent in-' swingingarm 9 having, in the resent instance, a contact plunger 10 in S idingoutu ward spring-thrust engagement with the inner periphery of theresistance coil =7. The plunger 10 has sliding radial movement in asocketed conductr part 11 of the arm 9 and this part has a stud 12projecting therefrom in exposed position axially of the swinging ax'isof the arm and at the side thereof exposed to the shaft 8. If therheostat unit is used in connection with a liquid levelindicatinginstrument, the shaftS may be connected to and actuated by themovement of a float ridin on the liquid, the level of which is to %edetermined. The manner of actuating the swinging contact arm, however,forms 'no part of the present invention and is, therefore, not shown.

Lead wires for therheostat control circuit are intended to enter theouter open end of the extension 2 and` to be engaged to lead' connectingbars 13-13 by terminal clamping screws 14, said lead bars beingprojected through the neck opening 5 and into the chamber 4 of thecasng, and one being connected to one terminal` end of the resistance'coil 7 by binding' screw 15, while the other has a spring lead finger 16mounte'd on its inner' end by a'binding screw 17. The free end of thefinger 16 bears on and makes electrical contact with the outer end ofthe stud 12, which projects axially from the swing- -ing contact arm ofthe rheostat The .two connecting bars are carried'in parallel spacedrelation by the two laterally spaced partition members 18 of insulatingmaterial. These partition members preferably comprise strips ofvulcanized fibre which fit -at their ends and lower bottom edges intorecesses 19 provided therefor n the side and bottom walls of the neckopening 5, the strips 18 being adapted to be slidingly placed into saidrecesses, as shown n Figs. 1 and 2. The connecting bars 13 are projectedthroug respective openi 20 provided throug 'the strps 18, such open-` ofsuitable size and shape to fit the end portions of the bars projectedtherethrough. The bars are prevented from endwise movement with res ectto the carrying strips' 18 when in assem led relation thereto by saidenlargements 21 provded on the strips s, best hw in Fig. 4.

When a set of bars 13 and insulated carrying-strips or members 18 havebeen assembled in proper relation, as shown n Fig. 4, they are insertedas a unit nto the nck portion 5 of the case 1 with the ends and bottomedges of the strips fittng into the recesses 19 of the case. This havingbeen done, the pocket or space between the insulating strips -18 andaround the central 1nterposed portions of the conneeting bars 13 isfilled with a material 22 (F ig. 2) 'whch is of an electrical insulatingnature and sufliciently fluid when appled to completely fill said spaceand to enter any crevices, Cracks or openings therein so as to cooperatewith the strips 18 and bars 13 to form an hermetic seal between therheostat chamber 4 and the wire terminal receiving chamber 2' in theextension 2. The material 22 should preferably be of'such a nature' asto become at least partially set so as to maintain its shape after beingapplied. This material should also be-of a nature to prevent beingattacked or disintegrated by or to render it insoluble in the liquid,the level of which is being determined, as in most applications thecasing 1 would be mounted in an opening. in the container and theextension 3 thereof projected into the container, thereby rendering itpossible in some cases for the liquid in the container entering thechanber 4. In some cases air pressure is applied to the liquid withinthe container to force it to a point of use,'and this pressure sonetimesmight enter the chamber 4, and it is, therefore, one of the purposes ofthe seal between such chamber and 'the wire terminal chamber 2' toprevent the leakage of such pressure' therebetween. In some cases aninsulating shellac may be employed as the material 22, and in othercases where gasoline or other hydrocarbon liquid is to be gauged acompound composed of glycerine and corn starch in substantially theproportion of two pounds of the former to four ounce's of the latter,thinned with water and boiled to a jelly-like consistency has been foundsuitable for use. This latter material forms the subject-matter of acopending application and is, therotore, not claimed herein.

The tops of the chanbers 4 and 2' are closed by covers 23 and 24,respectively, secured to the casing top by screws 24 or in any othersuitable manner. The cover 23 has a sealing or gasket tight fit o'n thetop of the casing and also coacts with the upper strips' 18 and withthetop of the materia therebetween.

I wish it understood that my invention is not limited to any specificConstruction arrangement or form of the parts, as t is capable ofnumerous modifications and changes without departing from the spirit ofthe claims.

Having thus described my invention, What I claim as new and desire tosecure by Letters Patent is: i

1. In a rheostat, a casing forming an open top casing, a cylindricalchamber for receiving rheostat contact parts and having a side openingtherefrom, a pair of spaced parallel insulating strips mounted in saidopening to close the same, electrical connecting member extendingthrough said strips and the space therebetween, sealing material fillingthe space between said stri veloping the contact mem Jers, and closuremeans mounted over said chamber and strips.

2. In a rheostat, a casing having a cylindrical chamber for receivngrheostat conopening having recessed side-walls, insulat-- ing stripsslidingly mounted in said recesses to form a double closure for theopening with a pocket therebetween, electrical' connecting membersextending through said strips and pocket, a sealing material disposed insaid pocket and elosely enveloping the connecting members, and removablecover means for said chambers and opening.

3. In combination, a casing forming a chamber for containing electricalparts and having a side opening leading therefron with spaccd recessesin the opening wall, insulating strips s'lidably mounted in saidrecesscs and forming transversely spaced closu'e members for the openingsaid strips having opening therethrough, a terminal connecting lead barprojected through said strip oponings and substantially filling the sameand having an enlarged portion in. the space between the strips forsholdoring against the strips, and a scaling material of flowingconsisteney when Originally applied disposed in and completely fillingthe space between said st'ips around said lead.

In testinony whereof I have hereunto signed by name to thisspecification.

` HARRY E. ADAMS.

s and' closely .en-

